Automated material handling system

ABSTRACT

An automated material handling system includes a plurality of bays, a continuous conveyer and at least one vehicle. Each bay has a plurality of tools and a stocker. The stocker is a rectangular solid having a first long side and a second long side. The first long side equips with a plurality of transferring ports connecting to the tools and the second long side equips with at least one transferring port connecting to the continuous conveyer. The vehicle is guided along the continuous conveyer for handling materials between the stockers.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The invention relates to an automated material handling system, andparticularly to an automated material handling system that transportsmaterials through a conveyer.

(2) Description of the Prior Art

With continuous advances of manufacturing technologies, the size ofmaterials (such as wafers and glass substrates) produced in thesemiconductor or photoelectric industry also increases constantly. Thosematerials generally are grouped in lots, and each of the lots contains25 pieces that are loaded in a cassette for transporting. Its weight istoo heavy for human to carry. Hence nowadays most plants adopt automatedmaterial handling system (AMHS) as the main facility to transport thecassettes.

Refer to FIG. 1 for a conventional single loop AMHS 10. It includes anoverhead single loop track 11. Bays 12 of various functions are setuparound the tracks 11 according to manufacturing process requirementplanning. The track 11 carries a plurality of overhead shutters (OHS)13, and each holds a cassette. The overhead shutters 13 move in and outof each bay 12 to transport materials. As the materials are transportedbetween the bays 12, it is generally called an Interbay transportsystem.

Each bay 12 has a stocker 14 and a plurality of tools 15. The tools 15in the same bay 12 are usually interrelated in the manufacturingprocess. Hence in the manufacturing process planning, one bay 12 may beseen as a manufacturing unit.

The stocker 14 mainly functions as a transfer station and a buffer zoneof material handling between the overhead shutters 13 and the tool 15.The conventional stocker 14 is a rectangular solid having two opposinglong sides, and each equips with a plurality of transferring ports 141.It has one short side connecting to the track 11, and a crane in thecenter to transport materials among the transferring ports 141. Thestocker 14 has one or two transferring ports 141 a and 141 b close tothe track 11 to serve as the material transport input and output portsto the overhead shutters 13. The rest transferring ports 141 areconnected to the tools 15 and serve as the material transport input andoutput ports between the tools 15 and the stocker 14.

The conventional single loop automated material handling system providesonly one way transport track. Control of vehicles and transport planningare simpler. Thus it is widely used in the industry. However, inpractice, there are still many drawbacks, notably:

-   -   a. Poor transport efficiency: Due to the conventional technique        transports only one way, in the event of rework is required in        the manufacturing process, the materials have to be moved back        to the original bay for processing. But the vehicle cannot be        moved backwards directly. It has to continuously travel forwards        and finish the entire journey of the track before returning to        the original bay to process rework. Hence transport efficiency        is undesirable.    -   b. When the conventional technique is adopted for one way        interbay transportation of a long distance, the problem of empty        vehicles occurs. This problem happens in the plant configuration        that requires to set up the bays at a long distance one way.        Hence vehicle dispatching has to take into account of the time        required to transport the empty vehicles.    -   c. When the conventional technique is adopted for sectional        interbay transportation, the system cost is higher. Referring to        FIG. 2, for the sectional interbay transportation, the entire        transport system is divided into several independent bay areas.        Between the independent bay areas, there is no need for material        transport. But to facilitate identification, different bays 12        have their numbers suffixed by different English characters. As        the conventional single loop handling system 10 has to be a        complete system, waste of system investment happens between the        independent bay areas (as the areas shown by the broken line).    -   d. The conventional techniques is constrained by the number of        the vehicles and cannot provide buffer zones for the working in        process (WIP).    -   e. The transport direction of the conventional techniques is        fixed, and cannot be altered or provide two-way transport        function.

Therefore, it is desirable to provide a smoother and more efficientmaterial handling system that can overcome the disadvantages associatedwith the conventional automated material handling system.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide anautomated material handling system to improve material handlingefficiency.

It is another object of the present invention to provide an automatedmaterial handling system to prevent transport of empty vehicles.

It is yet another object of the present invention to provide anautomated material handling system to reduce waste of system investmentbetween independent bay areas when sectional interbay transport isadopted.

It is still another object of the present invention to provide anautomated material handling system that provides more buffer zones tohold the materials for WIP.

It is a further object of the present invention to provide an automatedmaterial handling system that provides a two-way transport function tomake material handling more flexible.

To achieve the foregoing objects, the automated material handling systemaccording to the invention includes a plurality of bays, a continuousconveyer and a plurality of vehicles.

In one aspect, the bays may be arranged in a linear fashion or anannular loop according to manufacturing process planning. Each bay maybe a manufacturing unit consisting of a plurality of tools and astocker. The tools in the same bay generally are interrelated in themanufacturing process of the same manufacturing unit.

In another aspect, the stocker is a rectangular solid having a firstlong side and a second long side opposing each other that haverespectively a plurality of transferring ports. A crane is locatedbetween the two sides. The transferring ports on the first long side areconnected to the tools to transport materials therebetween. The secondlong side has at least one transferring port connecting to the conveyerto transport the materials between the vehicles and the transferringport. The crane transports the materials among the transferring ports inthe stocker. Hence the stocker may serve as a material transfer stationof each bay or a buffer zone.

In yet another aspect of the present invention, the continuous conveyermay be configured in a linear layout or a single loop layout, and adoptan overhead structure to be braced by a ceiling and the second side ofthe stocker. When the cassettes are carried by the vehicles, eachcassette may hold one lot of materials. The vehicles are traveled on theroute provided by the continuous conveyer, and the materials aretransferred in the stocker of each bay.

The automated material handling system according to the inventionincludes a first bay and a second bay. The first bay has a first two-waytransferring port on a second side of a stocker thereof, and the secondbay also has a second two-way transferring port on a second side of astocker thereof. A continuous conveyer is provided to perform two-waytransport between the first and the second two-way transferring ports.

When the manufacturing process of the two bays are identical, the twobays can backup each other during the manufacturing process, and providebuffer zones. In the event that the first bay provides a upstreamprocess and the second bay provides a downstream process, if thematerials in the second bay require rework, they may be transported backthrough the conveyer to the first bay for rework. In addition, toprevent the conveyer from creating errors during the two-way transport,the handling system of the invention further includes a programmablelogic controller and an interlock circuit equipment to link the signalsof the first bay and the second bay and control the transport directionbetween the first bay and the second bay.

Another embodiment of the present invention is adopted on sectionalinterbay material transport. It includes a plurality of independent bayareas, a plurality of sectional conveyers and a plurality of vehicles.

The bay areas in the embodiment set forth above are independent from oneanother. Each bay area includes at least one bay and one sectionalconveyer. Each bay includes a plurality of tools and a stocker. Thesectional conveyer is connected to at least one transferring portlocated on a second side of the stocker to transport materials betweenthe stocker and the vehicles along the travel route of the conveyer.

During material transport in the sectional interbay process, fabricationof the materials is finished in the bat area without the need oftransporting to other bay area for processing. Hence the sectionalconveyers are independent without connecting to one another. There is noneed to set up transport system between the bay areas, thus waste ofinvestment may be avoided. Moreover, since the sectional conveyers areindependent, transport direction may be designed individually, eitherone way or two-way, without the concern of interfering with one another.Hence this embodiment is more flexible in material transport planning.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be specified with reference to itspreferred embodiment illustrated in the drawings, in which:

FIG. 1 is a schematic view of a single loop automated material handlingsystem according to the prior art;

FIG. 2 is a schematic view of a sectional Interbay transport accordingto the prior art;

FIG. 3 is a schematic view of an automated material handling systemaccording to the first embodiment of the present invention;

FIG. 4 is a side view of a stocker according to the first embodiment ofthe present invention;

FIG. 5 is a schematic view of a conveyer supported by the ceiling andstocker according to the first embodiment of the present invention;

FIG. 6 is a schematic view of the second embodiment of the presentinvention; and

FIG. 7 is a schematic view of the third embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Refer to FIG. 3 for a first embodiment of the automated materialhandling system 30 of the present invention. It includes a plurality ofbays 31, a continuous conveyer 32 and a plurality of vehicles 33.

In an automated manufacturing process plant, the bays 31 are arrangedaccording to the manufacturing process planning. To facilitate materialtransport, the bays 31 are generally configured linearly or in anannular loop. Each bay 31 may be seen as a manufacturing unit consistingof a plurality of a plurality of tools 34 and a stocker 35. The tools 34generally are interrelated in the manufacturing process of themanufacturing unit.

The stocker 35 is a rectangular solid which has a first long side 351and a second long side 352 that have respectively a plurality oftransferring ports 353. The transferring ports 353 may be one way ortwo-way transferring ports. A crane 36 is located between the two sides.The transferring ports 353 on the first side 351 are connected to thetools 34 for transferring material therebetween. At least one of thetransferring ports 353 on the second side 352 is connected to thecontinuous conveyer 32 to transfer materials between the transferringport 353 and the vehicles 33. The crane 36 transfers the materials amongthe transferring ports 353. Hence the stocker 35 may serve as a materialtransfer station in the bay 31. In addition, each transferring port 353has a plurality of buffer zones 37 laid vertically (referring to FIG. 4)for transferring materials between the transferring ports 353 and thebuffer zones 37. Thus the stocker 35 may serve as the material bufferzone of the bay 31 during manufacturing process.

The continuous conveyer 32 may be configured in a linear layout or asingle loop layout and connect to the second side 352 of the stocker 35.As the second side 352 is the longer side of the stocker 35, when thecontinuous conveyer 32 adopts an overhead structure to be braced by aceiling 4, it can receive more support from the second side 352(referring to FIG. 5) and has a higher stability. By contrast, if theconveyer 32 is connected to the stocker 35 on the shorter side thatprovides less bracing area, it receives less bracing support, and thestability of the conveyer 32 also decreases.

When the vehicles 33 are used to carry cassettes, each cassette may holdone lot of materials. The vehicles 33 are traveled on the route providedby the continuous conveyer 32, and the materials are transferred in eachbay 31.

Refer to FIG. 6 for a second embodiment of the invention. The automatedmaterial handling system 60 includes a first bay 61 and a second bay 62.The first bay 61 has a plurality of first tools 611 and a first stocker63. The first stocker 63 has a first side 631 and a second side 632equipping with a first two-way transferring port 64. The second bay 62also has a plurality of second tools 621 and a second stocker 68. Thesecond stocker 68 has a third side 681 and a fourth side 682 equippingwith a second two-way transferring port 69. A continuous conveyer 65 isprovided to do two-way transport between the first two-way transferringport 64 and the second two-way transferring ports 69. When themanufacturing process of the two bays 61 and 62 are identical, they canbackup each other and provide a buffer zone.

Detailed implementation of the second embodiment is depicted as follow:when production of the first bay 61 reaches its full capacity but thesecond bay 62 still is idle, the buffered materials in the first bay 61may be transported through the conveyer 65 between the two bays 61 and62 to the second bay 62 for processing so that both bays 61 and 62 canachieve optimum production to increase the production efficiency of thewhole system. On the contrary, if the second bay 62 reaches fullproduction capacity but the first bay 61 is idle, materials may betransported through the conveyer 65 to the first bay 61 for processing.

The embodiment mentioned above may also be adopted to bays of differentmanufacturing processes as depicted below. If the first bay 61 providesa upstream process and the second bay 62 provides a downstream process,when the material in the second bay 62 requires rework, the material maybe transported by the conveyer 65 to the first bay 61 to do rework. Toprevent the conveyer 65 from creating errors during the two-waytransport, the handling system of the invention further includes aprogrammable logic controller (PLC) 66 and an interlock circuitequipment 67 to link the signals of the first bay 61 and the second bay62 and control the transport direction of the conveyer 65 between thefirst bay 61 and the second bay 62.

Refer to FIG. 7 for a third embodiment of the invention. It is adoptedto a sectional interbay material handling system 70. It includes aplurality of independent bay areas 71 a and 71 b, a plurality ofsectional conveyers 72 a and 72 b and a plurality of vehicles 73 a and73 b.

In the third embodiment, the bay areas 71 a and 71 b are independentfrom one another. Each bay area includes at least one bay 71 and asectional conveyer 72. Each bay 71 includes a plurality of tools 74 anda stocker 75. The sectional conveyer 72 is connected to at least onetransferring port 753 located on a second side 752 of the stocker 75.Vehicles 73 are located on the sectional conveyer 72 which provides atravel route to transport materials between the stocker 75 and thevehicles 73.

During material transport of the sectional interbay process, fabricationof the materials is finished in the bat area 71 without the need oftransporting to other bay area for processing. The sectional conveyers72 are independent without connecting to one another. Thus there is nowaste of transport system between the bay areas 71. Moreover, since thesectional conveyers 72 are independent, transport direction may bedesigned individually, either one way or two-way. Hence this embodimentis more flexible in material transport planning than the conventionaltechniques do.

While the preferred embodiments of the present invention have been setforth for the purpose of disclosure, modifications of the disclosedembodiments of the present invention as well as other embodimentsthereof may occur to those skilled in the art. Accordingly, the appendedclaims are intended to cover all embodiments which do not depart fromthe spirit and scope of the present invention.

1. An automated material handling system, comprising: a first bay havinga first tool and a first stocker, the first stocker having a first sideand a second side that have respectively a plurality of firsttransferring ports, the first tool being connected to the firsttransferring ports on the first side; a second bay having a second tooland a second stocker, the second stocker having a third side and afourth side that have respectively a plurality of second transferringports, the second tool being connected to the second transferring portson the third side; a continuous conveyer connecting at least one of thefirst transferring ports of the first bay to at least one of the secondtransferring ports of the second bay; and at least one vehicle movingalong the continuous conveyer for transporting materials between thestockers by the continuous conveyer.
 2. The automated material handlingsystem of claim 1, further comprising a crane between the first side andthe second side of the first stocker.
 3. The automated material handlingsystem of claim 1, wherein the continuous conveyer is an overhead typebracing by a ceiling and the stockers.
 4. The automated materialhandling system of claim 1, wherein the stockers have a plurality ofbuffer zones located in the vertical direction of the transferringports.
 5. The automated material handling system of claim 1, wherein thefirst transferring ports of the first bay and the second transferringports of the second bay are two-way transferring ports.
 6. The automatedmaterial handling system of claim 1, wherein the the continuous conveyeris a two-way conveyer.
 7. The automated material handling system ofclaim 6, further comprising a control logic, the control logic linkingsignals of the first bay and the second bay, the interlock circuitequipment controlling transport direction of the conveyer between thefirst bay and the second bay.
 8. The automated material handling systemof claim 6, further comprising an interlock circuit equipment, thecontrol logic linking signals of the first bay and the second bay, theinterlock circuit equipment controlling transport direction of theconveyer between the first bay and the second bay.
 9. A method oftransporting materials in an automated material handling system,comprising the steps of: providing a first bay having a first tool and afirst stocker, the first stocker having a first side and a second sidethat have respectively a plurality of first transporting ports, thefirst tool being connected to the first transferring port on the firstside; providing a second bay having a second tool and a second stocker,the second stocker having a third side and a fourth side that haverespectively a plurality of second transporting ports, the second toolbeing connected to the second transferring port on the third side;connecting at least one of the first transferring ports of the first bayto at least one of the second transferring ports of the second bay by acontinuous conveyer; and transporting materials between the stockers byat least one vehicle moving along the continuous conveyer.
 10. Themethod of claim 9, further comprising a step of loading the materials ina cassette before transporting.
 11. The method of claim 9, wherein thefirst transferring ports of the first bay and the second transferringports of the second bay are two-way transferring ports.
 12. The methodof claim 11, wherein the first bay provides a upstream manufacturingprocess, and the second bay provides a downstream manufacturing process,the continuous conveyer transporting the materials in a reversedirection from the second bay to the first bay.